Research Reveals Oldest Fossil Evidence of Plant-Fungi Relationship

Monday, August 1, 2011

A remarkable find from plant fossils that date to approximately 240 million years ago predates the last known plant-fungi association that occurs in specialized root structures, termed nodules, by 100 million years. The find indicates that this specialized form of symbiosis has an ancient origin.

Only the roots of a few families of modern coniferous plants contain fungi that form this symbiotic association with the plant. In this association – called a mycorrhizal association -- the fungus obtains carbon from the plant and the plant obtains certain types of nutrients from the fungus.

Although the fossil record of these families can be traced back into the early Mesozoic era, the oldest fossil evidence of root nodules previously came from the Cretaceous era.

Andrew Schwendemann, a doctoral student mentored by Thomas N. Taylor, studied fossil plant root nodules containing fungi. The preservation is so extraordinary that it allowed Andrew to examine the individual cells of both the root nodules and fungi.

Close examination showed that mutual associations between the conifer root nodules and fungi date back to at least the Mesozoic era, the period during which most of the modern conifer families first appeared.

The research paper was published in the Proceedings of the National Academy of Sciences today.

Andrew spent this past December and January in the Transantarctic Mountains in Antarctica collecting plant fossils like those from which these nodules were described. He and other research team members anticipate that the 10,300 pounds of fossils that were collected during the expedition and transported back to KU to be deposited in at the KU Biodiversity Institute will yield additional significant discoveries.